I'm building a system to control where my company's ads are placed. Amongst our concerns are potentially malicious code on the target page. Is there any library / database / system that can detect this content and is either open source or free?
~downer
In this case, you could look at Google's Safe Browsing API:
Single search:
http://www.google.com/safebrowsing/diagnostic?site=www.example.com
Signup for API key:
http://code.google.com/apis/safebrowsing/key_signup.html